The invention relates to a static mixer of plastic including an installation body for installation into a tubular mixer housing. This installation body has a longitudinal axis which is aligned in the direction of a fluid flowing into the installation body so that a mixing space can be spanned by the installation body. The mixing space has a cross-sectional flow area in a plane normal to the longitudinal axis which essentially corresponds to the cross-sectional flow area of the tubular mixer housing. The installation body includes a wall element for the division and/or deflection of the fluid flow in a direction deviating from the longitudinal axis.
Such a static mixer is, for example, known from EP1426099 B1. In this static mixer, two components are mixed with one another by means of a plurality of mixing elements of the same type in a three-part mixing process in which the material is first divided, then spread and displaced. This mixing process has to be carried out several times depending on the physical properties of the components. For this reason, the static mixer contains a plurality of installation bodies of the same construction arranged behind one another. These mixers are in particular used for the mixing of small quantities of the components, that is a few milliliters to approximately 1,000 milliliters. Accordingly, these mixers have a mixing space with a diameter of less than 16 mm with a length of more than 50 mm. This has the consequence that the wall thicknesses of the wall elements of this mixer can amount to less than 1 mm, often even less than 0.5 mm.
Such a static mixer in accordance with EP1426099 B1 of plastic is preferably manufactured in an injection molding process. The manufacture of a mixer of 30 mm length with a wall thickness of less than 3 mm using the injection molding process, as shown in FIG. 1 of this patent, was previously not possible since the flowpath from the injection point of the injection molding tool up to the oppositely disposed end of the mixer would require internal tool pressures which are too high. To be able to manufacture a static mixer having such small wall thicknesses economically in the injection molding process, each installation body is connected to the adjacent installation body via bar elements. These bar elements allow the polymer melt in the injection molding tool to move from one installation body to an adjacent installation body and to maintain the internal tool pressures below 1000 bar so that a failure of the injection molding tool can be prevented such as is shown in an arrangement of two installation bodies in accordance with FIG. 4 of EP 2 181 827 A1 which corresponds in its arrangement of wall elements and deflection elements to the embodiment in accordance with FIG. 15 or FIG. 17 of EP1426099 B1. As a major difference from EP1426099 B2, the bar elements of EP 2 181 827 A1 only serve for the connection of one installation body to an adjacent installation body. In contrast, the bar elements in accordance with FIG. 15 of EP1426099 B1 can extend over a plurality of installation bodies. The bar elements take up mixing space and were therefore avoided where possible or designed in accordance with the previous teaching such that they only connect some of the installation bodies with one another; in accordance with FIG. 15 of EP1426099 B1 a maximum of 5 installation bodies. It only became possible by the method in accordance with EP 2 181 827 to provide bar elements which each only connect two adjacent installation bodies to one another. It has, however, proved to be disadvantageous in this development that the stability of the mixing element made up of the installation bodies is also affected. It has in particular been found in the dispensing of viscous materials that the mixing element can break.